Transformer core



Aug. 30, 1932. H. G. Ross I TRANSFORMER CORE Filed Feb. 28, 1931 INVENTOR flay/2 G. Ross.

A Neon Tbbe Lenyf/r ATTORNEY Patented M 30, 1932 v UNITED STATES PATENT, OFFICE i HUGE G. B088, 0! 'WILKINSBUBG, rmmmvamnssmuoa '10 WESTINGHOUSE ELEC- TRIO & murac'runme comm, A CORPORATION 01 PENNSYLVANIA mama-0mm 001m Application fled February 88, 1931. Serial No. 519,115.

of power to a load the impedance of which may [vary through a wide range, high-reactance characteristics may be ut1l1zed to maintain a substantially constant, output or load current.

? As is known, the reactance of a transformer increases with the leakage magnetic flux. The reactance may, therefore, be controlled or adjusted to different values if some means 1s provided for changing the reluctance of the magnetic leakage path in the core structure of the transformer. 'My invention is primaril directed to a core construction for trans ormers wherein adjustment of the reture is assembled.

Generally stated, it is an object of my invention to provide, in a transformer, a core structure so disposed thatits partsmay be --readily adjusted to different relative positions to provide the different desired reactances for the transformer.

Another object of my invention is to provide, in a high-reactance transformer, a core of such construction that individual adjustment of each transformer unit is possible, during manufacture, to allow the meeting of varying reactance requirements without departure from a uniform or standard design of the core parts.

In practicing my invention, I provide a transformer core comprising two separate and relatively shiftable members so formed that their faces on opposite sides of the air gap in the magnetic leakage path are disposed at an angle with respect to the core axis. Relative shifting of the two members thus effects a change in length of the leakage gap without changing the magnetic properties of the other portions of the core and produces actance thereof may be made after the structhe desired changes in the transformer reactance.

The invention, both as to its organization and its method of operation, together with additional objects and advantages thereof, will best be understood. from the following description of s ecific embodiments, when read in connection with the accomanying drawing, in which:

Figure 1 is a perspective view of a transformer constructed in accordance with my invention;

Fig. 2 is a diagrammatic view of the core of the transformer of Fig. 1;

- Figs. 3 and 4 are similar views of transformer cores of other types disposed in accordance with my invention;

Fig. 5 is a circuit diagram illustrating one typical application in which the transformer of my invention is used, and

Fig. 6 is a diagram of curves illustrating the adjustable characteristics afforded by my invention when embodied in a transformer used in the system shown in Fig. 5.

Referring to the drawing, particularly Fig. 1 thereof, the transformer illustrated comprises a magnetic core structure comprising two separate members 10 and 11. The primary and secondary windings 12 and 13, respectively, surround the member 11 and are spaced apart b the central or magnetic ieakage leg 14 of the E-shaped core member I All .of the core parts are built up of sheets or laminations, as indicated in Fig. 1, to prevent excessive eddy currents. Suitable means for holding the laminations together may be provided in the form of rivets, shown at 15, or their equivalent.

The diagrammatic representation of Fig. 2 supplements the perspective drawing of Fig. 1, just described, and shows more clearly the core construction. Similar reference numerals are used in both figures.

To permit a simple and ready adjustment in the length of the magnetic leakage gap 16, the faces of the core members on opposite sides of the gap between the end of the central leg 14 of member 10 and core member 11 7 are formed at an angle of some such value I :as isindicated in the drawing with respect to the core axis, and rovision is made for shifting the core mem er 11 in an axial direction along member 10.- Suitable clamping means, shown at 17, are provided for holding the two core members firmly placein their adjusted positions, and may be loosened-3 to permit relative movement of the members.

It will be seen that a shift of core member 11 m to the-left shortens the gap 16, while a shift to the right lengthens the gap.

- Fig. 3 illustrates another embodiment ofmy invention which, as will be seen, provides for a reactance adjustment comparable to that of Figs. 1 and 2. J Primary and secondary windings 12 and 13 surround the sym-- metrically formed winding member 18 which cooperates with the two similar 'E-shaped core members 19 in .the mannerillustrated,

The two air gaps 20 in the magnetic leaka e j circuits'may be adjusted in length by shi ting the position of core member 18 with'respect to that of the cooperating members 19.

. to effect a desired change in thetransfo reactance." I H In Fig; 4, my invention is shown applied to a core structure adapted to carry, on the slidably disposed bar memberi2l, one pri mar-y winding 22 and two'secondary windings 23. Cooperating with bar. member 21 are 7 similar core members 24. The two sets of air gaps 25, and26 may be adjusted in length by shifting the position of member 21, in. the

- manner already explained.

. One of the appllcations to which a trans former of the type just described is particularly suited is for the energization of neon electric signs. In this, as in other applications, it is desirable that the transformer used shallbe capable of satisfactory performance over a wide range of difi'erent operating condltlons, and the core construction of my inventlon makes posslble such desired broad adaptability. Fig. 5 illustrates a transform-v er, shown generally at 27, supplied with powerfrom a constant-potential source 28 a'nddisposed to energize either of two neonfilled glass tubes 29 and 30. These tubes may be considered as being of substantially simi .lar design but of different-lengths as indicated by dimensions A'and B.- I

" A transformerof the'ordinary constant pOtential-design, when used in system of this application, would supply a relatively high currentto'the' short length of neon tube 29 and a relatively low'current to the much longer length oftube 30, since theresistance is substantially a'direct function of the tube length. Atransformer of high leakage re- ,a'ctance, such asis described. and'illustrated "1n the drawlng overcomesjthls ob ection, since itssecondary-current characteristic may be made substantially flat, as'indicated by curve 31 of Fig. 5. It will be evident, from examination of. thiscurve, that the current supplied to neontube A is only slightly greater than the current supplied to the 1011 er tube B,'the difierence-bemg of such sma ma tude that the neon-tube operation is satis c tory in both cases.

4 Through the provision of an adjustable feature -in e magnetic leakage member of ahi h-reactancetransformer, it is possible to shift :the position of the secondary-current characteristic by correspondingly changing the length of the leakage air gap. Again, in

neon-tube applications, this feature is partlcularly valuable, since it isfrequentlydesirable tooperate the tubes at current values above or below some intermediate value to ob- I tam, respectively, high brilliancy at the ex-i pense of tube electrode life or long life for the electrodes at a correspondingly lower brilliancy.

.Assumin that. the transformer of 1 is connecte in the-circuit of Fig. 4, as at 27,

the secondary-current characteristic 31- of Fig. "5 would obtain for some intermediate value of air gap 16. Shifting the core member 11 to the left effects a shortening of gap 16, and shifts the secondary-current charac-.

teristic to a lower value, such as in indicated at 32 in Fig. 5. Likewise, a shift of core member 11 to the ri ht correspondingly lengthens the gap 16 an raises the secondarycurrent characteristic of the transformerto some higher value, as indicated at 33.

It-will, therefore, be seen that a transformer embodying a core structure of the type just described not only has 'a substantially. =flatsecondary-current characteristic but likewise, through the provision of reactance adjustment, is capable of shifting this secondary characteristic to meet the needs of a variety of different applications and, in so doing, makes use of core parts of simple,-inexpensive and easily manufactured design.

7 Although I have shown and described cer tain specific embodiments of my invention, I am fully aware that many modifications.

thereof are possible. My invention, therefore, is not to be restricted except insofaras is necessitated by theprior art and by the spirit of the appended claims.

.I claim as my invention:

1. A magnetic core structure, comprising" cooperating members disposed and shaped to 2. In a ma etic core structure comprising two cooperating members having a plurality 'of surfaces thereof in en agement and shaped to provide a pluralit o magnetic paths one or more .of which inc udes an air gap between opposing surfaces of said two members, the faces of the core members on opposite sides of said air ap being parallel to each other and disposed at an angle with respect to the core-member axes, the position of one member relative to that of the other being slidably adjustable alon said engaging surfaces to effect a change in the air-gap length.

3; In a transformer, a magnetic core comprisin in combination, an E-shaped member and a ar member cooperating therewith to bridge the two outside projecting legs and to form an air ga at the end of the central leg thereof, the aces of the core members on opposite sides of said gap being parallel to each other and disposed at an angle with respect to the bar member axis, and provision for shifting, in an axial direction, the position of the bar member relative to that of the E member to effect a change in the air-gap length without affecting the magnetic properties of the outside core legs.

4. A transformer comprising a magnetic core havin an E shaped member and a cooperating ar member disposed to bridge the ends of the projecting legs of the E shaped member, a primary winding and a secondard winding disposed about said bar member on the respective lengths thereof included between the central leg and each of the two outside legs of the E member, said core members being so formed that a ga is left between the bar member and the en of the central core leg, the core member faces at said gap being parallelwith each other and disposed at an angle with respect to the bar member axis, one of said core members being movablein an axial direction with respect 'to the other core member to thereby adjust the length of said gap.

5. In a transformer, a magnetic core comrising, in combination, a winding-carrying bar member and a plurality of E shaped members cooperating therewith, said core members being so shaped and disposed that the two outside projecting legs of each of the E members are bridged by the said bar member and air gaps are provided between the bar members and the ends of the intermediate projecting legs of said E members, the faces of the,core members on opposite sides of said gaps being parallel to each other and disposed at an angle with respect to the bar member axis, said core members being so disposed as to provide for adjusting their relative positions by a sliding movement therebetween to effect a change in theseveral airgap lengths.

6. A transformer comprising a magnetic core having a winding-carrying bar member projecting legs of each E member are bridged by the said ar member and an air gap is formed between it and the end of the central projecting leg of each E member, the faces of said gap being parallel with each other and disposed at an angle with respect to the bar member axis, said bar member being so disposed as to be movable in an axial direction relative to the E members to efiect a chan e in the air-gap lengths without affecting the magnetic characteristics of the outside core le s.

In a-transformer, a magnetic core comprising, in combination, a winding-carrying bar member and one or more outer core members cooperating therewith, each of said outer members comprising a common longitudinal section and four legs projecting perdendicularly from one side thereof in spaced relation along the said section length, said core members being so shaped and disposed that the ends of the projecting legs of the outer member are bridged by the said bar member and air gaps are formed between it and the end of each of the two intermediate projecting legs, the faces of each of said air gaps being parallel with each other and disposed at an angle with respect to the bar member axis, and provision for shifting in an axial direction the position of the barmember relative to that of the cooperating outer members to effect a change in the lengths of the several air gaps.

8. In a transformer, a magnetic core comprising, in combination, a winding-carrying bar member and one or more outer core members cooperating therewith, each of said outer members comprising a common longitudinal section and a plurality of'legs projecting perpendicularly from one side thereof in spaced relation along the said section length, said bar member and the outer member projecting legs being so shaped and disposed that the ends of two or more of said legs are bridgedby the bar member, and air gaps are formed between it and the ends of each of the remaining legs, the faces of each of said air gaps being parallel with each other and disposed at an angle with respect to the barmember axis, and provision for shifting in an axial direction the position of the bar member relative to that of the cooperating outer members to effect a change in the lengths of the several air gaps.

In testimony whereof, I have hereunto subscribed my name this 17th day of February, 1931. HU

GH G. ROSS.

its 

